oh, it's called the speaker wire =) unfortunately speaker wires may have different connectors (jack, speak-on, xlr...) or no connector like you actually need, so that's a 2-conductor speaker wire.
your local music shop should have a roll of some 2-conductor speaker cables that they will cut you. any local electric shop will make you one as well if you bring your cable and say: "it's from a 50wt speaker pair, I need one a foot longer".